Although various bank cards are widely used now, the circulation of cash remains predominant. Some criminals use high-tech means to imitate and forge value documents such as banknotes, causing serious harm to our society. In order to prevent the circulation of imitated value documents such as fake banknotes, there are increasing demands for accuracy and portability of value document distinguishing device. However, nowadays, distinguishing devices with relatively high accuracy mainly include large scale devices such as Banknote-Testing Device and ATM, which have high price and less portability, and therefore the application places of these devices are greatly restricted. In order to solve this problem, some simple devices such as fluorescence pen are emerged on the market; however, these portable devices have difficulties in detecting and distinguishing a value document.
A problem the skilled in the prior art encountered is: if the accuracy of a value document distinguishing device is to be improved, the accuracy for capturing images by the value document distinguishing device must be ensured. For this end, the value document distinguishing device needs to use a stable single light source to capture image, so as to improve the sharpness and reality of a value document image, therefore, the hardware structure and application places of the value document distinguishing device are restricted, and the value document distinguishing device with high accuracy has complex structure, high price and less portability. A value document distinguishing device with simple structure, low price and portability, however, has less accuracy for distinguishing.
Therefore, there is a need for a value document distinguishing device with high accuracy and portability.